Evaluation of Non-Celiac Gluten Sensitivity in Patients with Previous Diagnosis of Irritable Bowel Syndrome: A Randomized Double-Blind Placebo-Controlled Crossover Trial

Two randomized crossover multicenter studies investigating gastrointestinal symptoms after bread consumption in individuals with noncoeliac wheat sensitivity: do wheat species and fermentation type matter?

BACKGROUND

Many individuals reduce their bread intake because they believe wheat causes their gastrointestinal (GI) symptoms. Different wheat species and processing methods may affect these responses.

OBJECTIVES

We investigated the effects of 6 different bread types (prepared from 3 wheat species and 2 fermentation conditions) on GI symptoms in individuals with self-reported noncoeliac wheat sensitivity (NCWS).

METHODS

Two parallel, randomized, double-blind, crossover, multicenter studies were conducted. NCWS individuals, in whom coeliac disease and wheat allergy were ruled out, received 5 slices of yeast fermented (YF) (study A, n = 20) or sourdough fermented (SF) (study B, n = 20) bread made of bread wheat, spelt, or emmer in a randomized order on 3 separate test days. Each test day was preceded by a run-in period of 3 d of a symptom-free diet and separated by a wash-out period of ≥7 d. GI symptoms were evaluated by change in symptom score (test day minus average of the 3-d run-in period) on a 0-100 mm visual analogue scale (ΔVAS), comparing medians using the Friedman test. Responders were defined as an increase in ΔVAS of ≥15 mm for overall GI symptoms, abdominal discomfort, abdominal pain, bloating, and/or flatulence.

RESULTS

GI symptoms did not differ significantly between breads of different grains [YF bread wheat median ΔVAS 10.4 mm (IQR 0.0-17.8 mm), spelt 4.9 mm (-7.6 to 9.4 mm), emmer 11.0 mm (0.0-21.3 mm), P = 0.267; SF bread wheat 10.5 mm (-3.1 to 31.5 mm), spelt 11.3 mm (0.0-15.3 mm), emmer 4.0 mm (-2.9 to 9.3 mm), P = 0.144]. The number of responders was also comparable for both YF (6 to wheat, 5 to spelt, and 7 to emmer, P = 0.761) and SF breads (9 to wheat, 7 to spelt, and 8 to emmer, P = 0.761).

CONCLUSIONS

The majority of NCWS individuals experienced some GI symptoms for ≥1 of the breads, but on a group level, no differences were found between different grains for either YF or SF breads.

CLINICAL TRIAL REGISTRY

clinicaltrials.gov, NCT04084470 (https://classic.

CLINICALTRIALS

gov/ct2/show/NCT04084470).

The Role of Diet in the Management of Irritable Bowel Syndrome: A Comprehensive Review

Irritable bowel syndrome (IBS) is a highly prevalent gastrointestinal disorder that has a significant impact on the general population. The suboptimal medical treatments available for IBS contribute to its large economic burden. The pathophysiology of IBS is complex, and treatments often focus on managing specific symptoms. Many individuals with IBS associate their symptoms with specific food intake, leading to increased scientific research on the role of diet in managing IBS. Dietary management has become a crucial aspect of IBS treatment, with initial recommendations focusing on adopting a healthy eating pattern and lifestyle. This comprehensive review aims to synthesise the current literature on the impact of diet on IBS, exploring various dietary approaches to managing IBS, including the low fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAP) diet, gluten-free diet, Mediterranean diet, and tritordeum-based diet. It presents evidence from both experimental and observational studies and summarises the underlying dietary triggers in IBS, including gut microbiota dysbiosis, visceral hypersensitivity, and immune activation. In addition, it explores the efficacy and limitations of the key diet and lifestyle recommendations provided by dietary guidelines and scientific literature, highlighting the importance of individualised dietary strategies tailored to the unique needs of different types of IBS patients. By elucidating the complex interplay between diet and IBS pathophysiology, this review provides valuable insights into optimising dietary management approaches for improving symptom control and enhancing the quality of life for individuals with IBS.

Impact of Gluten-free Diet on Anthropometric Indicators in Individuals With and Without Celiac Disease: A Systematic Review and Meta-analysis

PURPOSE

Previous studies have found that a gluten-free diet (GFD) may have improve obesity-related factors. For this reason, we conducted a systematic review and meta-analysis to investigate the effect of a GFD on anthropometric indicators.

METHODS

We performed a systematic search in databases from inception until July 12, 2022. We included all relevant articles that evaluate efficacy of a GFD on anthropometric indicators in patients with and without celiac disease (CD). Random-effects models were applied to combine the data. The main outcomes were then analyzed using weight mean differences (WMDs) and 95% CIs.

FINDINGS

A total of 27 articles met the eligible criteria and were included. Pooled results from the random-effects model indicated that the GFD has no significant effect on any of the factors of anthropometry, including weight (WMD, 1.20 kg; 95% CI, -1.16 to 3.55 kg; P = 0.319), body mass index (WMD, 0.70 kg/m2; 95% CI, -0.45 to 1.84 kg/m2; P = 0.233), waist circumference (WMD, 0.92 cm; 95% CI, -1.34 to 3.17 cm; P = 0.497), and body fat (WMD, 1.02%; 95% CI, -0.38% to 2.42%; P = 0.153). The subgroup results indicated that after implementation of a GFD significant increased weight and body fat occurred in patients with compared with without CD. In addition, the effect of this diet on the increase of BMI and body fat in the intervention of more than 48 weeks was significantly higher.

IMPLICATIONS

The results of the present study indicate that a GFD can have a significant and beneficial effect on weight and body fat in patients with CD.

Evaluation and management of irritable bowel syndrome

ABSTRACT

Irritable bowel syndrome (IBS) is a common diagnosis that providers encounter in primary and specialty care. IBS is characterized by chronic abdominal pain and altered bowel habits. The American College of Gastroenterology recently released an updated guideline for the evaluation and management of patients with IBS. According to the guideline, it remains important to confirm diagnosis based on criteria and lack of alarm signs; IBS should not be a diagnosis of exclusion. Management should be focused on addressing altered bowel habits and global symptoms using a multidisciplinary approach.

Is it time to rethink the burden of non-coeliac gluten sensitivity? A systematic review

INTRODUCTION

Non-coeliac gluten sensitivity (NCGS) is still a poorly defined clinical condition. This review aims to describe the clinical features of subjects with a symptomatic response to gluten intake, and to estimate the prevalence of NCGS.

EVIDENCE ACQUISITION

Literature search was conducted in accordance with PRISMA recommendations. The PubMed database was searched for original articles until 1^st June 2020.

EVIDENCE SYNTHESIS

We identified 30 relevant articles, including 14 studies that investigated NCGS through a double-blind, placebo-controlled crossover trial (DBPCC), and 16 that examined the role of gluten in causing symptoms without a DBPCC. We found that regardless of the diagnostic work up, gluten-sensitive patients were predominately middle-aged females complaining of abdominal pain, bloating and diarrhea. The pooled prevalence of NCGS after DBPCC was 24% (5-34%). Subjects with irritable bowel syndrome or self-reporting gluten intolerance accounted for the vast majority of the patients who did not start a DBPCC. A symptomatic response to a gluten-free diet (GFD) occurred in between 7% and 93% of patients. No data on long-term outcomes of NCGS individuals were reported.

CONCLUSIONS

Clinical features of NCGS patients did not differ among all the included studies, whereas prevalence figures are rather heterogeneous. Long-term benefit of a GFD on these patients still needs to be ascertained.

Diagnostic Dilemma, Possible Non-celiac Gluten Sensitivity: Consideration in Approach and Management

Non-celiac gluten sensitivity (NCGS) is clinically identified as a condition where a percentage of the population reports intestinal and/or extraintestinal symptoms caused by gluten and/or wheat ingestion, and they are tested negative for celiac disease (CD) on the basis of specific serology and histopathology. NCGS should be labelled after the exclusion of CD and wheat allergy. This population reports improved symptoms on a gluten-free diet. Despite great interest and work on NCGS, much remains unknown about its pathogenesis. A positive and improved response to a gluten-free diet for a limited period of time (e.g., six to eight weeks), followed by retrieval of symptoms in case of gluten intake, is presently considered to be the best strategy for confirmation of diagnosis.

A middle-aged lady came for medical attention with concerns of weight loss, lethargy and abdominal discomfort. On investigations, her serum transglutaminase IgA was found to be largely raised. The patient was switched to a gluten-free diet with suspicion of CD. Upper GI endoscopy was done one week after being on a gluten-free diet. Both endoscopy with histopathology was negative for villous atrophy and increased intraepithelial lymphocytes. Later human leukocyte antigen (HLA) testing was found to be negative for CD, leading to a diagnostic conundrum. On the basis of remarkable symptom improvement on a gluten-free diet, drop in transglutaminase levels, negative biopsy and HLA testing, the diagnosis was made as possible NCGS. Considering gluten-related disorders are rising and not much is known about NCGS, we aimed to present this case to create awareness and raise questions regarding diagnosis, need for specific monitoring and implications on the management.

The effect of gluten in adolescents and young adults with gastrointestinal symptoms: a blinded randomised cross-over trial

BACKGROUND

The popularity of the gluten-free diet and sales of gluten-free products have increased immensely.

AIMS

To investigate whether gluten induces gastrointestinal symptoms, measured by self-reported questionnaires, as well as mental health symptoms in adolescents from a population-based cohort.

METHODS

The eligible participants (n = 273) were recruited from a population-based cohort of 1266 adolescents and had at least four different gastrointestinal symptoms. Phase one (n = 54) was a run-in phase where the participants lived gluten-free for 2 weeks. If they improved they continued to phase 2 (n = 33), a blinded randomised cross-over trial. Participants were blindly randomised either to start with 7 days of gluten, eating two granola bars containing 10 g of gluten or to 7 days on placebo, eating two granola bars without gluten, followed by the reverse and separated by a 7-day washout period. The effects of the intervention on gastrointestinal symptoms and mental health symptoms were assessed.

RESULTS

In total, 54/273 participants entered the run-in phase and 35 were eligible for randomization. A total of 33 were randomised and 32 completed the trial. The median age was 20.3 (IQR 19.2-20.9) and 32/33 participants were females. Compared with a placebo, gluten did not induce gastrointestinal symptoms. The difference in the average VAS was -0.01 (95% confidence interval -2.07 to 2.05). Nor did we find a difference in the outcomes measuring mental health.

CONCLUSION

Compared with placebo, adding gluten to the diet did not induce gastrointestinal symptoms or worsened mental health in adolescents recruited from a population-based cohort. The trial registration number is NCT04639921.

Effects of a gluten challenge in patients with irritable bowel syndrome: a randomized single-blind controlled clinical trial

Non-celiac gluten sensitivity (NCGS) and irritable bowel syndrome (IBS) frequently overlap. Although, gluten-free diet (GFD) and low fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAP) improve the IBS clinical picture, many aspects remain unclear. Therefore, we designed a study to evaluate gluten tolerance, anxiety and quality of life in a specific study population. Fifty IBS patients were asked to follow a low FODMAP strict GFD for 6 weeks and were then randomly allocated to the following groups for a further 6 weeks: (A) receiving 8 g/day of gluten for 2 weeks; gluten-tolerating subjects received 16 g/day for 2 weeks and then 32 g/day for a further 2 weeks; (B) continuing to follow a low FODMAP strict GFD; and (C) receiving a gluten-containing diet. After the first 6 weeks, symptom scores significantly improved. Pain severity, bloating and total score were significantly decreased in the GFD and in the high-gluten groups, while the satiety score significantly increased in group C. Between-group analysis revealed significant differences for pain severity (p = 0.02), pain frequency (p = 0.04) and impact on community function (p = 0.02) at the end of the study. Our findings suggest that low FODMAP strict GFD could be prescribed in IBS patients and would reduce anxiety and improve the quality of life.

Effects of a gluten-reduced or gluten-free diet for the primary prevention of cardiovascular disease

BACKGROUND

Cardiovascular diseases (CVD) are a major cause of disability and the leading cause of death worldwide. To reduce mortality and morbidity, prevention strategies such as following an optimal diet are crucial. In recent years, low-gluten and gluten-free diets have gained strong popularity in the general population. However, study results on the benefits of a gluten-reduced or gluten-free diet are conflicting, and it is unclear whether a gluten-reduced diet has an effect on the primary prevention of CVD.

OBJECTIVES

To determine the effects of a gluten-reduced or gluten-free diet for the primary prevention of CVD in the general population.

SEARCH METHODS

We systematically searched CENTRAL, MEDLINE, Embase, CINAHL and Web of Science up to June 2021 without language restrictions or restrictions regarding publication status. Additionally, we searched ClinicalTrials.gov for ongoing or unpublished trials and checked reference lists of included studies as well as relevant systematic reviews for additional studies.

SELECTION CRITERIA

We planned to include randomised controlled trials (RCTs) and non-randomised studies of interventions (NRSIs), such as prospective cohort studies, comparing a low-gluten or gluten-free diet or providing advice to decrease gluten consumption with no intervention, diet as usual, or a reference gluten-intake category. The population of interest comprised adults from the general population, including those at increased risk for CVD (primary prevention). We excluded cluster-RCTs, case-control studies, studies focusing on participants with a previous myocardial infarction and/or stroke, participants who have undergone a revascularisation procedure as well as participants with angina or angiographically-defined coronary heart disease, with a confirmed diagnosis of coeliac disease or with type 1 diabetes.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed eligibility of studies in a two-step procedure following Cochrane methods. Risk of bias (RoB) was assessed using the Cochrane risk of bias tool (RoB2) and the 'Risk Of Bias In Non-randomised Studies - of Interventions' (ROBINS-I) tool, and the certainty of evidence was rated using the GRADE approach.

MAIN RESULTS

One RCT and three NRSIs (with an observational design reporting data on four cohorts: Health Professionals Follow-up Study (HPFS), Nurses' Health Study (NHS-I), NHS-II, UK Biobank) met the inclusion criteria. The RCT was conducted in Italy (60 participants, mean age 41 ± 12.1 years), two NRSIs (three cohorts, HPFS, NHS-I, NHS II) were conducted across the USA (269,282 health professionals aged 24 to 75 years) and one NRSI (Biobank cohort) was conducted across the UK (159,265 participants aged 49 to 62 years). Two NRSIs reported that the lowest gluten intake ranged between 0.0 g/day and 3.4 g/day and the highest gluten intake between 6.2 g/day and 38.4 g/day. The NRSI reporting data from the UK Biobank referred to a median gluten intake of 8.5 g/day with an interquartile range from 5.1 g/day to 12.4 g/day without providing low- and high-intake categories. Cardiovascular mortality From a total of 269,282 participants, 3364 (1.3%) died due to cardiovascular events during 26 years of follow-up. Low-certainty evidence may show no association between gluten intake and cardiovascular mortality (adjusted hazard ratio (HR) for low- versus high-gluten intake 1.00, 95% confidence interval (CI) 0.95 to 1.06; 2 NRSIs (3 cohorts)). All-cause mortality From a total of 159,265 participants, 6259 (3.9%) died during 11.1 years of follow-up. Very low-certainty evidence suggested that it is unclear whether gluten intake is associated with all-cause mortality (adjusted HR for low vs high gluten intake 1.00, 95% CI 0.99 to 1.01; 1 NRSI (1 cohort)). Myocardial infarction  From a total of 110,017 participants, 4243 (3.9%) participants developed non-fatal myocardial infarction within 26 years. Low-certainty evidence suggested that gluten intake may not be associated with the development of non-fatal myocardial infarction (adjusted HR for low versus high gluten intake 0.99, 95% CI 0.89 to 1.10; 1 NRSI (2 cohorts)). Lowering gluten intake by 5 g/day also showed no association on the primary prevention of non-fatal and fatal myocardial infarction (composite endpoint) in linear dose-response meta-analyses (adjusted HR 1.02, 95% CI 0.98 to 1.06; 1 NRSI (2 cohorts)). Coronary risk factors  Type 2 diabetes From a total of 202,114 participants, 15,947 (8.0%) developed type 2 diabetes after a follow-up between 22 and 28 years. There was low-certainty evidence that a lower compared with a higher gluten intake may be associated with a slightly increased risk to develop type 2 diabetes (adjusted HR 1.14, 95% CI 1.07 to 1.22; 1 NRSI (3 cohorts)). Furthermore, lowering gluten intake by 5 g/day may be associated with a slightly increased risk to develop type 2 diabetes in linear dose-response meta-analyses (adjusted HR 1.12, 95% CI 1.08 to 1.16; 1 NRSI (3 cohorts)). Blood pressure, low-density lipoprotein level, body mass index (BMI) After six months of follow-up, very low-certainty evidence suggested that it is unclear whether gluten intake affects systolic blood pressure (mean difference (MD) -6.9, 95% CI -17.1 to 3.3 mmHg). There was also no difference between the interventions for diastolic blood pressure (MD -0.8, 95% CI -5.9 to 4.3 mmHg), low-density lipoprotein levels (MD -0.1, 95% CI -0.5 to 0.3 mmol/L) and BMI (MD -0.1, 95% CI -3.3 to 3.1 kg/m²).  No study reported data on adverse events or on other outcomes. Funding sources did not appear to have distorted the results in any of the studies.

AUTHORS' CONCLUSIONS

Very low-certainty evidence suggested that it is unclear whether gluten intake is associated with all-cause mortality. Our findings also indicate that low-certainty evidence may show little or no association between gluten intake and cardiovascular mortality and non-fatal myocardial infarction. Low-certainty evidence suggested that a lower compared with a higher gluten intake may be associated with a slightly increased risk to develop type 2 diabetes - a major cardiovascular risk factor. For other cardiovascular risk factors it is unclear whether there is a difference between a gluten-free and normal diet. Given the limited findings from this review predominantly based on observational studies, no recommendations for practice can be made.

Celiac Disease: Fallacies and Facts

Our understanding of the pathophysiology of celiac disease has progressed greatly over the past 25 years; however, some fallacies about the clinical characteristics and management persist. Worldwide epidemiologic data are now available showing that celiac disease is ubiquitous. An elevated body mass index is common at the time of the diagnosis. The gluten-free diet (GFD) is an imperfect treatment for celiac disease; not all individuals show a response. This diet is widely used by people without celiac disease, and symptomatic improvement on a GFD is not sufficient for diagnosis. Finally, the GFD is burdensome, difficult to achieve, and thus has an incomplete efficacy, opening exciting opportunities for novel, nondietary treatments.

Irritable Bowel Syndrome: Food as a Friend or Foe?

Irritable bowel syndrome (IBS) affects 10% to 15% of the population and often is difficult to treat with available pharmacologic agents. Dietary therapies for IBS are of particular interest because up to 90% of IBS patients exclude certain foods to improve their gastrointestinal symptoms. Among the available dietary interventions for IBS, the low FODMAP diet has the greatest evidence for efficacy. Although dietary therapies rapidly are becoming first-line treatment of IBS, gastroenterologists need to be aware of the negative effects of prescribing restrictive diets and red flag symptoms of maladaptive eating patterns.

Non-Celiac Gluten Sensitivity in the Context of Functional Gastrointestinal Disorders

Gluten-free diets are increasingly chosen in the Western world, even in the absence of a diagnosis of celiac disease. Around 10% of people worldwide self-report gluten-related complaints, including intestinal and extra-intestinal symptoms. In most cases, these subjects would be labeled as patients suffering from irritable bowel syndrome (IBS) who place themselves on a gluten-free diet even in the absence of celiac disease. In some instances, patients report a clear benefit by avoiding gluten from their diet and/or symptom worsening upon gluten reintroduction. This clinical entity has been termed non-celiac gluten sensitivity (NCGS). The symptoms referred by these patients are both intestinal and extra-intestinal, suggesting that similarly to functional gastrointestinal disorders, NCGS is a disorder of gut-brain interaction. It remains unclear if gluten is the only wheat component involved in NCGS. The mechanisms underlying symptom generation in NCGS remain to be fully clarified, although in the past few years, the research has significantly moved forward with new data linking NCGS to changes in gut motility, permeability and innate immunity. The diagnosis is largely based on the self-reported reaction to gluten by the patient, as there are no available biomarkers, and confirmatory double-blind challenge protocols are unfeasible in daily clinical practice. Some studies suggest that a small proportion of patients with IBS have an intolerance to gluten. However, the benefits of gluten-free or low-gluten diets in non-celiac disease-related conditions are limited, and the long-term consequences of this practice may include nutritional and gut microbiota unbalance. Here, we summarize the role of gluten in the clinical features, pathophysiology, and management of NCGS and disorders of gut-brain interaction.

Gluten Free Diet for the Management of Non Celiac Diseases: The Two Sides of the Coin

A lifelong adherence to a gluten-free (GF) diet is currently the only treatment for Celiac disease (CD), an autoimmune disorder that arises after gluten ingestion in individuals who are genetically predisposed. The gluten intake exerts toxic effects through several pathways involving gut barrier integrity, intestinal microbiota composition and immune system stimulation. However, despite the great benefit of GF diet for CD patients, its use has been debated. Indeed, individuals who adopt this diet regime may be at risk of nutrient deficiencies. Emerging evidence supports a beneficial effect of a GF diet also for other pathological conditions, including gluten-related disorders (GRD) often associated to CD, such as Non celiac gluten sensitivity (NCGS) and Dermatitis Herpetiforme (DH) as well as Irritable bowel syndrome (IBS) and Diabetes. This suggests a pathogenic role of gluten in these conditions. Despite the growing popularity of GF diet among consumers, to date, there are limited evidences supporting its use for the management of non-celiac diseases. Therefore, in this review, we discuss whether the GF diet could really improve the general quality of life of patients with GRD and non-GRD conditions, keeping in mind its sensorial limitations and nutritional inadequacies. In addition, we discuss the current motivations, leading to the use of a GF diet, despite the inferior quality of GF products respect to those containing gluten.